The invention relates generally to a seating system having a linearly aligned chair, footrest and work station and more specifically to a seating system apparatus having an alignment member wherein the chair, the footrest and the work station are aligned and the chair position and the footrest position as well as the height and inclination of the footrest are adjustable to maintain the torso and limbs of an operator in an optimum low stress, low fatigue position.
Increasing productivity is both an ongoing process and challenge to industry. During the past several decades, attention was directed to improving production by automating repetitious tasks. The use of robotic production equipment represents the current zenith of such an approach. Accordingly, attention has been redirected to other facets of the work environment particularly the work station, through the science of ergonomics which espouses the correspondence between form and function and the logical and coherent relationship between man and machine.
Ergonomic thinking has benefited both the worker and employer and significant improvements in productivity have been achieved through the application of ergonomic principles. An appropriate ergonomic application field relates to sedentary repetitious work tasks wherein a worker may remain seated during an entire shift at a video display terminal (VDT), punch press or similar work station. Repetitious work tasks result in fatigue and physical stress which may lead to physical injury, commonly known as repetitive strain injury or cumulative trauma disorder.
A classic example of non-ergonomic design is the mismatch of desk and chair heights. If chair seat height is not properly adjusted relative to the height of a desk and the size of the operator, the operator may be forced into a kyphotic or rounded back posture which increases neck and back strain or forces the operator to function with his arms in excessive shoulder, adduction or rotation which increases shoulder strain.
Much attention has been paid to the proper positioning and maintenance of the body. The patent literature discloses numerous seating devices of distinct configurations directed to diverse purposes.
For example, U.S. Pat. Nos. 482,745, 488,707 and 491,098 teach barber and dental chairs having integral footrests. The chair disclosed in the first patent is disposed on a movable frame which engages the floor whereas the latter two patents disclose chairs rotatably secured to fixed supports. In the '745 patent the footrest is coupled to the base of a chair configured in a manner similar to a platform rocker. Thus, as the chair cushion moves, the dimensional relationship between it and the footrest changes as well. In the latter two patents, the footrest is an extension of the chair and, accordingly, moves with the chair seat and back maintaining a constant dimensional relationship therebetween.
U.S. Pat. No. 4,348,051 teaches a chair having a mechanism for adjusting its height and a circular footrest surrounding the chair height adjustment mechanism which is coupled to the height adjustment mechanism.
U.S. Pat. No. 3,858,938 discloses a wheelchair having leg and foot supporting means. At the lower forward portion of the chair seat, a pair of L-shaped arms are pivoted to receive and selectively elevate the lower legs. In U.S. Pat. No. 4,538,857, a similar wheelchair construction permits vertical adjustment of the seat height as well as the footrest height and inclination thereof.
Attention has also been paid to footrests as a means of properly positioning the body. For example, U.S. Pat. No. 483,265 teaches a seat and footrest combination. The device disclosed therein includes a pivoted seat board which may be inclined to support the user in a partially erect position or disposed horizontally to provide conventional seating. U.S. Pat. No. 3,653,715 teaches an adjustable footrest wherein the forward and rearward portions of the footrest may be independently adjusted by means of spring biased pivoted legs to provide both height and inclination adjustment.
U.S. Pat. No. 4,427,234 teaches a leg rest having a first support designed to fit under a knee adjacent portion of a person's thighs and a second support designed to receive the feet of a person. The two supports are coupled by a hinged adjustable extension which facilitates storage of the footrest. The foot engaging portion of the footrest is said to be easily pivotable. Another footrest is disclosed in U.S. Pat. No. 4,813,742. Here, a footrest of a size certain has an upper surface oriented at an angle between 9 and 13 degrees. The footstool is intended for relieving strain and preventing orthopedic problems for users engaged in activities such as nursing a baby.
Complex seating configurations have also been developed. U.S. Pat. No. 4,369,997 discloses a sinuous, articulated chair having an elevated seat surface and footrest. The seat surface and the interconnected footrest and backrest may be adjusted from a position in which the seat surface is substantially horizontal and the device functions as a conventional chair to a highly inclined seat surface where the chair functions primarily as a standing rest.
U.S. Pat. No. 4,768,831 teaches a work station or operators seat having a foot control. The seat is adjustable along a fixed inclined axis which rises and recedes from the work station. A footrest is similarly supported along the inclined guide and may be adjusted independently relative to the seat. The feet of the operator are received upon an actuator plate which is pivotally adjustable. The position of the actuator plate controls, for example, the speed of the associated work station equipment. U.S. Pat. No. 4,779,922 discloses another work station wherein a video display terminal or similar device is positioned before an operator seated in a lounge-type chair. The chair is rockable about a horizontal axis adjacent the forward portion of the seating surface. As the seated operator rocks about the horizontal axis, the distance between the operator and the video display terminal and an associated input device remains relatively constant.
While the foregoing seating and support devices address specific task related human seating and support problems, they seldom ensure proper use of the device. That is, basic human nature encourages a person to utilize the seating provided in a personal way. Consequently, a person voluntarily though not consciously may subject himself to unnecessary repetitive physical stress situations because the seating and support equipment has been utilized improperly. It has been found that instruction in proper techniques to prevent such injuries has proven ineffective in spite of the fact that many ergonomic seating designs such as those discussed above have been produced and utilized.
Significant research and design effort has developed desk and chair designs which provide proper support and limb placement in an attempt to limit stresses on the back, neck, shoulder and upper extremity anatomy resulting from prolonged sitting at a work station. In spite of the efforts of designers and manufacturers, however, the operator seldom takes advantage of the intended design and assumes a natural and comfortable though, as noted above, harmful posture. For example, if the back of a chair is designed to support the lumbar region of the back and the operator does not sit back against such lumbar support but sits on the front edge of the chair, the well designed lumbar back support is useless and offers no lumbar support. The benefits of the carefully designed chair are thus lost and what was designed to be a comfortable, low fatigue work station fails to provide the intended performance.
From the foregoing, it is apparent that improvements in the configuration and of combination seating system and work station components is both desirable and beneficial to increase productivity.